DESCRIPTION (Taken directly from the application): Each major SCOR project requires the analysis of CFTR chloride (CI-) channel function in polarized epithelia from airway, gastrointestinal tract (GI tract), or both. As such, a specialized and focused CF Assay Core is essential to the progress of each component of the SCOR program. This core will focus on the establishment and assay of polarized epithelial monolayers and their analysis in Ussing chambers measuring transepithelial ion transport and assist in vivo nasal potential difference (PD) measurements. The central aim of the Assay Core is to provide in vivo or in vivo-like electrophysiological assays to assess CFTR chloride (CI-) channel function. The primary role of this focused core is to provide Ussing chamber electrophysiological analysis of CFTR Cl- channel function in a polarized epithelium, either borne in a tissue or established in primary culture on a collagen-coated permeable filter support. This is an in vivo-like assay. Polarized epithelia for analysis in Ussing chamber electrophysiological systems will be obtained/derived from two sources: 1) intact mouse intestinal tissue; and/or 2) epithelial cells isolated from airway tissue and grown in primary culture on filter supports as a polarized monolayer. A secondary role for the PI of the core will be to consult in the experimental design of nasal potential difference (PD) measurements designed to study CFTR Cl- channel function in mouse models of CF or more newly established transgenic animals. This is an in vivo assay. The unique aspects of these projects necessitate a specialized Assay Core. In particular, the isolation of tissues and epithelial cells from those tissues from existing and newly designed transgenic mouse models for the above four projects for Ussing chamber studies is essential. Close communication with Dr. Rozmahel and the Mouse Genetics Core will be essential to maximally utilize mouse models for these projects. Handling of the mice will be performed within the Mouse Genetics Core. It is anticipated that novel results will be found, regardless of outcome, to more fully understand the pathogenesis of CF. It is also anticipated that novel methods will be developed to better assay CFTR function in vivo or with in vivo-like paradigms.